Perhaps nothing defines an individual more strongly than sex. Along with one's designation as male or female are a slew of differences relating to anatomy, physiology, and behavior. In the laboratory rat, one such dimorphic characteristic in the brain is the expression of arginine vasopressin (AVP). Male rats have twice as many cells expressing AVP in the bed nucleus of the stria terminalis (BST) and the medial amygdala (MA) as do female rats. In rats and mice, AVP in the lateral septum, modulates social behaviors such as social recognition and aggression. Because of its striking dimorphism and its role in social behaviors, sexually dimorphic expression of AVP in the BST can serve as an interesting model system in which to study the differentiation of neuropeptide expression in a behavioral circuit. The work presented here addresses three primary issues. First, to study the development of AVP expression, a developmental marker is needed to identify cells that may be induced to express AVP in adulthood. Based on birthdating studies, I have found that galaninergic neurons represent a pool of cells from which AVP expression may be derived; the majority of galaninergic neuron cell birth overlaps with neurogenesis of AVP cells and there is no sexually dimorphic pattern of BrdU-labeling in galaninergic cells. Secondly, in order to understand cellular mechanisms of neuropeptide induction more precisely, I determined the extent to which male and female brains are bipotential with respect to AVP expression. Using neonatal hormone manipulations and later in situ hybridization, I found that female rats may be completely masculinized with post-natal hormone treatment. Finally, knowing that post-natal testosterone alone can completely masculinize AVP expression, I used similar techniques to determine the form of testosterone that is active in masculinization of AVP expression. I not only found that neonatal treatment with estradiol benzoate is sufficient for masculinizing AVP expression but that neonatal treatment with dihydrotestosterone propionate can also increase AVP expression in the BST, but only to a level intermediate that produced by estradiol benzoate and oil treatment.
| Identifer | oai:union.ndltd.org:UMASS/oai:scholarworks.umass.edu:dissertations-3622 |
| Date | 01 January 2002 |
| Creators | Han, Tina M |
| Publisher | ScholarWorks@UMass Amherst |
| Source Sets | University of Massachusetts, Amherst |
| Language | English |
| Detected Language | English |
| Type | text |
| Source | Doctoral Dissertations Available from Proquest |
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